Improvement in screw-cutting machines



C. BURLEIGH &. J. PUTNAM.

SCREW-CUTTING MACHINE.

No.175,026. Patented March 21,-1876.

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NJUERS. PKOTO L|THDGRAPHEE. WASHINGTON. D c

UNITED STATES CHARLES BUBLEIGH AND J OHNPUTNAM, OF FITOHBURG, MASSACHUSETTS,

PATENT Orr-roe ASSIGNORS TO THE PUTNAM MACHINE ooMPANY, or sAME PLACE.

IMPRQVEMENT IN SCREW-CUTTING MACHINES.

\ I Y a Specification forming part of Letters Patent No. [7 5,026, dated March 21, 1876 application filed March 3,1816.

To all whom it may concern:

Be it known that we, OHARLEs BURLEIGH and JOHN PUTNAM, both of Fitchbnrg, in the county of Worcester and State of Massachu setts, have invented an Improvementin Screw- Threading Machines, of which the following is a specification This invention relates to details of construction, which willbe best understood from description of the "drawing which illustrates an embodiment of our invention- Figure 1 being a central longitudinal section of the rotating tubular die holder and carrier, showing the details of construction, combination, and' adjustment which are the peculiarities of our invention; Fig. 2 being an end view of the die-carrying holder or chuck with its face cap removed. Fig. 3 shows, in plan, some of the important parts.

a is the hollow mandrel to whiclf power is applied, it being mounted in suitable bearin gs. The die-holder or chuck b is either made integral with the mandrel or is fixed thereunto;

It is slotted radially to receive the steel diepieces 0, said slots making guideways for the dies to be moved in, thefront edges of the dies being flush with the front face of the holder 1). The circumference'of b is screwthreaded to fit nut-threads formed in the removable die-coveriug piece d, and both on b and in d sections of the threads are removed, so that by a sliding movement the inner face of d can be brought against the front faces of b and c, it being held in place by a slight rotary motion, which causes the screw-threads to interlock, removal of the cover d being effected by reversal of said ,motions. This makes an effective union of the parts b (1, and by it little time is consumed in removal and replacement of (1 when changing dies or removing them for examination.-

The mechanism for bringing the dies to their cutting position, and for witl'idrawing them from their work, is as follows: Each diepiece is interchangeable for others, and is shaped, as shown, at its upper end to hook upon the end of the short arm of lever e, pivoted to lg atf, the long arm of lever 0 being connected by links 9 to abent lever, h, pivoted at i to a sleeve, j, to which a sliding movement can be imparted on the mandrel a by means of a lever, k, worked by the attendant. This surrounds the sleeve j, in the further outer end of which a groove is turned, into which fits a loose ring, Z, in halves, the pivotscrews m in lev'er It entering sockets in the ring I. If the links g were connected directly to the sleeve j instead of to the lever h, which is connected to said sleeve, it will be evident that, by the connections described, movement of sleeve j toward the holder b would cause the cutting-ends of the dies 0 to approach a common center--,viz., the axis of rotation of mandrel a, and also that movement of sleeve j in the reverse direction would cause retraction of said dies-from said center; but to adjust the dies so that their greatest movement inward shall adapt them to any given diameter (within the capacity of the machine) of a rod or bolt to be screw-threaded, one end of the bent lever'h engages in a groove turned in the piece at, which piece has n It threads which lit screw-threads made on tl e periphery of the sleeve j, so that it will be evident that if piece nis rotated so as to move toward the holder 1) the dies will be retracted from the axis of rotation, while if movement of 'n is in the contrary direction the dies will be adjusted toward the center of rotation.

Thus it will be obvious that by rotation of n'the dies are adjusted with relation to the finished size of screws to be cut, and that by reciprocation of j the dies are brought to the position where they do their work, or are suddenly disengaged from the screw-threads which they have formed;

An y convenient number of dies may be used and connected as shown butin practice three dies are found to operate best. When the dies are in position to operate upon a bolt, the

lines passing through the pivots ,of the links g are nearly, if not quite, at right angles with the axis of rotation, so that no amount of outward pressure exerted on the cutting-ends of the dies will cause sliding movement of the sleeve j.

In Fig. 1 the position of parts shown is that in which the adjustment of the dies is for the smallest size of screws to which the machine is adapted, while the position of the dies is 2. The mechanism for adjusting the dies to work of various diameters,consisting of the threaded slide j, threaded and grooved piece n, levers h, links g, and levers 0, combined andarranged to operate substantially as described.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

CHARLES BURLEIGH. JOHN PUTNAM. Witnesses:

LOUIS D. BARTLETT, P. O. BURR. 

